Sunday, June 20, 2010

When Bacteria Share Enzymes -- Road to Microbial Fuels

Harry Beller, an environmental microbiologist who directs the Biofuels Pathways department for JBEI’s Fuels Synthesis Division, led a study in which a three-gene cluster from the bacterium Micrococcus luteus was introduced into the bacterium Escherichia coli. The enzymes produced by this trio of genes enabled the E. coli to synthesize from glucose long-chain alkene hydrocarbons, predominantly 27:3 and 29:3 (no. carbon atoms: no. C=C bonds). _GCC

Learning to mix and match genes from different species of bacteria (and other life forms) will allow humans to custom manufacture a wide range of high value chemicals, plastics, fuels, feeds, and most other things that people need for daily living. But don't tell anyone in the government -- they'll find a way to outlaw the practise. No doubt at the instigation of their faux environmentalist comrades.

These long-chain alkenes can then be cracked—reduced in size—to obtain shorter hydrocarbons that are compatible with today’s engines and favored for the production of advanced lignocellulosic biofuels.

In order to engineer microorganisms to make biofuels efficiently, we need to know the applicable gene sequences and specific metabolic steps involved in the biosynthesis pathway. We have now identified three genes encoding enzymes that are essential for the bacterial synthesis of alkenes. With this information we were able to convert an E. coli strain that normally cannot make long-chain alkenes into an alkene producer.

—Harry Beller

It has long been known that certain types of bacteria are able to synthesize aliphatic hydrocarbons, which makes them promising sources of the enzymes needed to convert lignocellulose into advanced biofuels. However, until recently, little was known about the bacterial biosynthesis of non-isoprenoid hydrocarbons beyond a hypothesis that fatty acids are precursors.

We chose to work with M. luteus because a close bacterial relative was well-documented to synthesize alkenes and because a draft genome sequence of M. luteus was available. The first thing we did was to confirm that M. luteus also produces alkenes.

—Harry Beller

Beller and his colleagues worked from a hypothesis that known enzymes capable of catalyzing both decarboxylation and condensation should be good models for the kind of enzymes that might catalyze alkene synthesis from fatty acids. Using condensing enzymes as models, the scientists identified several candidate genes inM. luteus, including Mlut_13230. When expressed in E. coli together with the two adjacent genes —Mlut_13240 and 13250—this trio of enzymes catalyzed the synthesis of alkenes from glucose. Observations were made both in vivo and in vitro.

This group of enzymes can be used to make aliphatic hydrocarbons in an appropriate microbial host but the resulting alkenes are too long to be used directly as liquid fuels. However, these long-chain alkenes can be cracked—a technique routinely used in oil refineries—to create hydrocarbons of an appropriate length for diesel fuel.

—Harry Beller

The next step in the research is to learn more about how these three enzymes work, particularly Mlut_13230 (also called OleA), which catalyzes the key step in the alkene biosynthesis pathway—the condensation of fatty acids.

We’re also studying other pathways that can produce aliphatic hydrocarbons of an appropriate length for diesel fuels without the need for cracking. Nature has devised a number of biocatalysts to produce hydrocarbons, and our goal is to learn more about them for the production of green transportation fuels.

—Harry Beller

Working with Beller on this study were Ee-Been Goh and Jay Keasling. The three were the co-authors of a paper that appeared earlier this year in the journalApplied and Environmental Microbiology, titled “Genes Involved in Long-Chain Alkene Biosynthesis in Micrococcus luteus.”

The faux environmentalists are attacking nuclear power, biomass, coal, oil sands, oil shales, bio-ethanol, shale gas, and any other form of potentially clean and abundant energy.

These faux environmentalists promote dead-end wind and solar, huge rat holes of resource waste that will leave us gasping for energy and dying from lack of industrial, transportation, agricultural infrastructure.

The zombie apocalypse is on, and a large portion of the zombies currently reside in Washington DC -- living it up on the taxpayer's dime. Destroying the future, and writing IOU's that even your great-great-great-great grandchildren will not be able to pay.